A couple nights ago, I found my lost silver dollar. Today, I lost my USB rechargeable tail light. I had it clipped on to the under-seat bag on my 29er using the "backpack clip." It must have flown off when I was crossing bumpy terrain. I discovered its absence when I parked my bike. If I didn't have to be at work so soon after that, then I would have backtracked. It would probably have been easy to find because it was in flash mode. I looked for it on the way home and couldn't find it. The battery had certainly died by that time and maybe someone else picked it up.
That Serfas USL-TL60 is an amazing light for the money. I will use the TL-411 until I either find my old light on the side of the trail or give up and order a new USL-TL60. It's nice that Serfas uses a universal mount so that I can interchange the lights.